1865-1945 1945- 20thcentury american americannationalcharacteristics aspectpsychologique casestudies collectiefgeheugen collectivememory conditionssociales crises crises(aspectospsicológicos) crises(sciencessociales) general histoire historischesereignis history históriadosestadosunidos kollektivesgedächtnis local memory memória(aspectossociais) mémoirecollective nationalcharacteristics politiekecrises psychischestrauma psychologicalaspects psychologicalaspectsofcrises socialaspects socialconditions state unitedstates étudesdecas